Injecting testosterone will increase both total and free testosterone. It will NOT add to the existing testosterone you have, it doesn't work that way. It will shut down what natural testosterone production you have, which in your case isn't enough.

Total testosterone - this represents all the testosterone in your body.
Free testosterone - this is a portion of your total, the part that isn't bound. Free testosterone is your usable testosterone.

Symptoms are based on how much free testosterone you have. You can have extremely high total testosterone and still have low testosterone symptoms if your free testosterone is too low. And you can have low free testosterone despite high total testosterone, which would be due to elevated levels of SHBG.

Hair loss - keep in mind one of the causes of hair loss is low testosterone. If your testosterone levels remain low it may cause you to lose some of your hair. If you take testosterone, it may also cause you to lose some of your hair, although uncommon with TRT doses. In either case, you have to be genetically predisposed to male-pattern baldness, meaning you were going to lose the hair at some point anyway, but low levels of testosterone or testosterone use itself can potentially speed it up. The propecia may or may not help.

200mg of testosterone every 10 days, you generally want to go no more than a week without an injection. The active half-life is only 6 days or so. The terminal half-life is 12 days or so, but terminal isn't what's important. Some doctors get the terminal and active half-life mixed up or they don't know there's a difference. Inject and around days 5-6 levels will creep quickly back to baseline, so then you have to wait a few more days before you inject again. You may be creating a bit of a roller coaster with your levels. Some men actually split their dose in half and take two injections per week. If the dose were 200mg per week, they might split it into two 100mg shots per week, say on Monday and Thursday. This prevents the fluctuation in levels. Twice a week isn't always needed but generally injections should be at least every 7 days.

Arimidex, that's a fairly hefty dose. It's usually best to start testosterone for 5-6wks and then measure estradiol. You want to use the Sensitive Estradiol panel, not the standard and then you can gauge how much anti-estrogen medication you need. This is important as some men do not need any. If you don't need any or are taking more than you need and lowering your E2 levels too much, this can cause numerous symptoms, many of which are identical to low testosterone.